In today's environmentally conscious society, the environmental impact of disposal containers is of great concern. One area of concern that remains to be adequately addressed is the recyclability of paperboard packages coated with polymeric materials such as polyethylene. While such coated paperboard packages are generally recyclable, a small but significant portion of the composite paperboard packages now commercially available cannot be efficiently or economically recycled with current technology. The inability to recycle 100 percent of the polymeric material and paperboard substrate of the coated paperboard packages is due, at least in part, to the low-value of fiber-contaminated polymer that must be disposed of by means other than recycling.
Various techniques for the partial recycling of coated paperboard composites are commercially available. One common technique is the repulping of the coated paperboard whereby polymeric coating material is separated from the paperboard substrate by floatation. Another technique is the use of organic solvents to dissolve the polymeric coating and thereby separate the polymeric coating from the substrate. While these techniques are relatively simple, at best only about 98 wt. % of the paperboard fiber is recoverable and typically only 50 wt. % to 75 wt. % of the paperboard fiber is recoverable. Furthermore, the polymeric material which may contain as little as 2 wt. % fiber has little or no value due to its fiber content. If solvents are used to dissolve the polymeric material, expensive distillation, extraction or other separation techniques are required to recover the polymeric material from the solvent. Consequently, the polymeric material separated from the paperboard substrate is generally landfilled or incinerated.
If, on the other hand, essentially all of the paperboard substrate and polymeric coating material is recoverable, there would be an economic incentive to recycle more of the polymeric material coated paperboard containers. Currently, the economics of recycling such coated paperboard containers are adversely impacted by the cost for landfill and/or incineration of the low-value, fiber or solvent contaminated polymeric material.
It is therefore an object of the invention to provide compositions and methods which enhance the recoverability of polymeric material coated paperboard composites.
Another object of the invention is to provide a method for recycling and recovering polymeric coatings and paperboard substrates from polymer coated paperboard composites using commercially available repulping techniques.
Yet another object of the invention is to provide a method for increasing the rate of recovery of polymeric coating material and paperboard substrate in a commercially acceptable manner.
Other objects and benefits of the invention will be evident from the ensuing description and appended claims.